Currently, since HFC134a, which is used as a refrigerant in car air conditioning systems, has a large global warming potential (GWP), HFO1234yf, which has a small GWP, has emerged as a promising new refrigerant candidate to replace HFC134a. For example, Japanese Unexamined Patent Application Publication No. 2009-074017A proposes a composition comprising a refrigerant such as HFO1234yf and a lubricating oil.
Additionally, conventionally, laminated structures of a rubber and a resin comprising an innermost layer formed from a polyamide resin material in order to suppress the permeation of a refrigerant have been commonly used for rubber hoses for use in car air conditioning systems.